Windshield Wiper/washer Linkages problems of the 2004 Audi A4

My 2004 Audi A4 3. 0 cabriolet has windshield wipers which at about 8,000 miles of wear began to make an unbearably loud, rythmically repetitive sound on the driver's side. The selling dealer, cherry hill imports, has repeatedly looked at the problem and said there is nothing unusual about this sound, but the car did not do it when it was new. In severe weather , I have resorted to turning off the wipers for a few seconds at a time in order not to be hypnotized by the repetitive sound of the defect. This, of course, is a safety hazard, but I feel being put to sleep while driving is more dangerous, should the defect lead to that. Dealerships besides cherry hill imports have replaced the blades on the car, but the effect of this remedy was non-existent. I feel it is my duty to request the aid of the nhsta to save the lives of Audi owners who labor under this hazard, as well as my own. Thanks.